The pending closure of Vermont Yankee has raised a lot of interest in our energy choices and policies that will affect Vermont’s growth, business, environment and economy. To have meaningful discussions, we need some way to compare all of the energy options and technologies.

That is actually surprisingly difficult, but one way is to compare the price of electricity, considering things like operations and maintenance, the transmission investment needed and the source’s capacity needed to meet demand — resulting in a relative cost per kilowatt-hour. For comparison, these are normalized to a 100 percent capacity factor — meaning that its cost is adjusted for day-night solar, variable winds, nuclear refueling, plant maintenance and operations costs in addition to the cost of the fuel.

This is a comparison value only, since we can’t really get solar or wind 100 percent of the time, but it does reflect the true and real relative costs of each source. To be fair, I also included a comparison of the greenhouse gas damage that each source causes.

I used research conducted in December 2012 by the U.S. Energy Information Administration to price a variety of energy sources at what it called levelized and normalized cost per kilowatt-hour. I also used a 2012 Yale University study of the emission of greenhouse gases by energy source given in grams of carbon dioxide per kilowatt-hour.

I then multiplied these two numbers together and divided by 1,000. I call this value the living cost factor. The LC factor gives us a relative comparison value that combines the total costs of our electricity production and the environmental damage for each energy source.

Hydroelectric has the lowest with a living cost factor of 0.7, largely because its emissions factor is only 4. This is by far the best choice, except hydropower is available in less than 1 percent of the land mass of the United States and almost everywhere that it can be implemented, it already has been. The opportunity for growth of hydroelectric use on utility scales is almost zero.

Nuclear is next with an LC factor of 1.9; it has the second lowest cost (below geothermal) and the third lowest emissions (after geothermal and wind). It can be placed at any location and can integrate into the existing transmission grid at the lowest cost level. Surprisingly, despite the hysteria and fear of opponents, nuclear has the lowest historical environmental and human damage toll of all of these energy sources. This includes considerations for any and all nuclear accidents back to 1950.

Biomass is next with an LC factor of 2.4. It would be lower, but the variable operations and maintenance and the recurring fuel costs are second highest only to natural gas. Biomass includes a number of different technologies and base fuels that have not been able to scale up to the level needed to produce utility-scale biomass power without creating competition with food production, lumber use or high fuel costs.

Wind is the next lowest with an LC factor of 3.1. It obviously has a low emissions factor and zero recurring cost for fuel, but when normalized for a 100 percent capacity factor, the cost per kilowatt-hour is $255. In reality, it can never achieve 100 percent capacity. The standard value used for capacity within the wind power industry is 33 percent, but Vermont wind farms are all averaging less than 25 percent and some as low as 19 percent. Even offshore wind farms are rated only at 37 percent. This low a capacity value makes it necessary to maintain a 100 percent backup power production capability at all times, which is why, even in Denmark, wind power has not reduced the need for a single base-load-capable coal-fired plant.

Offshore wind has an LC factor of 6.6, which is driven by the second highest capital costs (second only to solar thermal) and second lowest emissions of 11, which gives a cost of $599 per kilowatt-hour. Offshore wind has the highest costs related to integration into the transmission grid and the second highest fixed operations and maintenance costs — second only to solar thermal — and it has a very limited number of locations that it can be cost-effectively installed.

Geothermal is next — using the heat of the Earth to create the steam for the generators. At $97 per kilowatt-hour it has the lowest cost because it has essentially no fuel costs, but it does have an emissions number of 45. Its LC factor is 4.4. Unfortunately, only about 3 percent of the United States is suitable for efficient access to geothermal power. Outside of those areas, the costs of drilling to the depth needed would drive the cost up significantly.

Solar photovoltaic is next with an LC factor of 26.6. This jump in LC value comes mostly from the third highest capital costs, giving the third highest power cost at $577 per kilowatt-hour. It also has the second highest cost related to integration into the transmission grid. The cloudy-day and nighttime power loss issue means that, like wind, it is necessary to maintain a 100 percent backup power production capability at all times, which is why, even in Germany, solar power has not reduced the need for a single base-load-capable coal-fired plant.

Solar thermal uses mirrors to produce the heat needed to spin turbines. This power source has the highest capital investment, the highest costs related to integration into the transmission grid and the highest power costs at $1,308 per kilowatt-hour, giving an LC factor of 67. Until an efficient technology is found to store utility-scale electric power, solar and wind will not be a viable base-load power source.

The next to last is natural gas with an LC factor of 98 — with an emission factor of 469. Natural gas also has the highest variable operations and maintenance and recurring fuel costs. Although the Yale study says that natural gas has less than half the emissions of coal, it did not include in its study the damage to the groundwater, aquifers and surface pollution from fracking. Gas is still a significant emitter of greenhouse gases, but it is doing much greater harm to the underground fresh water supply.

The final power source is coal, which surprisingly has only the fourth lowest power costs at $141 per kilowatt-hour, but with an emissions factor of 1,001, it drives the LC factor to 141 — which is 201 times larger than for hydroelectric.

Taken in this context and based on real world scientific analysis and comparisons, the logical choice among those fuels that are viable for base-load production is nuclear.